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ComCompatibleVersionAttribute Class

Indicates to a COM client that all classes in the current version of an assembly are compatible with classes in an earlier version of the assembly.

System.Object
  System.Attribute
    System.Runtime.InteropServices.ComCompatibleVersionAttribute

Namespace:  System.Runtime.InteropServices
Assembly:  mscorlib (in mscorlib.dll)

[ComVisibleAttribute(true)]
[AttributeUsageAttribute(AttributeTargets.Assembly, Inherited = false)]
public sealed class ComCompatibleVersionAttribute : Attribute

The ComCompatibleVersionAttribute type exposes the following members.

  NameDescription
Public methodComCompatibleVersionAttributeInitializes a new instance of the ComCompatibleVersionAttribute class with the major version, minor version, build, and revision numbers of the assembly.
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  NameDescription
Public propertyBuildNumberGets the build number of the assembly.
Public propertyMajorVersionGets the major version number of the assembly.
Public propertyMinorVersionGets the minor version number of the assembly.
Public propertyRevisionNumberGets the revision number of the assembly.
Public propertyTypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
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  NameDescription
Public methodEqualsInfrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeReturns the hash code for this instance. (Inherited from Attribute.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIsDefaultAttributeWhen overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
Public methodMatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Explicit interface implemetationPrivate method_Attribute.GetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.InvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)
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You can apply this attribute to assemblies.

By default, the Tlbexp.exe (Type Library Exporter) uses an assembly's version number to calculate class identifiers (CLSIDs). All public, COM-visible classes receive new CLSIDs each time you export a new assembly version.

You can apply the ComCompatibleVersionAttribute attribute to force all CLSIDs for classes in the current version of an assembly to be the same as CLSIDs for classes in an earlier version of the assembly. As long as the CLSIDs remain the same, a legacy COM application can use the later version of a compatible assembly after you uninstall the original assembly. If you apply the System.Runtime.InteropServices.GuidAttribute to a class to explicitly set its CLSID, the ComCompatibleVersionAttribute has no effect.

The properties of this attribute combine to form the four parts of an assembly version. Always specify the lowest version that the current assembly is backward compatible with so that version is used to calculate all CLSIDs in the assembly.

The following example shows how to specify assembly version 1.0.0.0 in an assembly with a higher version number. Regardless of the new assembly version, all CLSIDs in the assembly are generated using version 1.0.0.0 instead of using the current assembly version.


using System;
using System.Reflection;
using System.Runtime.InteropServices;

[assembly: AssemblyVersion("3.0.0.0")]
[assembly: ComCompatibleVersion(1,0,0,0)]
namespace MyNamespace
{
    public class TheClass
    {
        // Insert code.
    }
}


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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